<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=`, initial-scale=1.0">
    <title>Document</title>
    <style>
        .container{
            position: absolute;
        }

        .left{
            width: 200px;
            position: absolute;
            left: 0;
        }

        .main{
            margin-left: 100px;
            margin-right: 100px;
        }

        .right{
            width: 200px;
            position: absolute;
            right: 0;
        }
    </style>
</head>
<body>
        <div class="container">
            <div class="left" style="border: 1px solid black">left Sidebar</div>
            <div class="main" style="border: 1px solid blue;">main content</div>
            <div class="right" style="border: 1px solid red;">right Sidebar</div>
        </div>
</body>
</html>